Production of artificial filaments and other products



PATENT OFICE PRODUCTION OF ARTIFICIAL FILAMENTS AND OTHER PRODUCTS Henry Dreyfus, London, and William Ivan Taylor, Spondon, near Derby, England, assignors to Celanese Corporation of America, a corporation of Delaware No Drawing. Application May 6, 1932, Serial No. 609,774. In Great Britain June 25, 1931 17 Claims.

This invention relates to the manufacture of filaments, threads, yarns, ribbons and the like from solutions of cellulose acetate or other cellulose esters or ethers.

As is well known, in the early days of the manufacture of cellulose acetate filaments considerable difiiculty arose from the fact that the filaments produced had a relatively fiat crosssection and exhibited the disadvantage of scin- 10, tillation when in fabric form. These diificulties were to a considerable extent eliminated by U. S.

Patent No. 1,688,531, according to which filaments of rounder cross-section are obtained by employing spinning solutions containing upwards of and especially to or more, of cellulose acetate. Similarly, improved results were obtained by employing cellulose derivatives of high viscosity characteristics, see in particular U. S. Patent No. 1,872,701. In recent years the tendency of commercial practice has been to spin at high speeds, i. e. speeds of over 180 metres per minute, for example speeds of 200 to 300 or 400 or more metres per minute in the case of dry spinning. At the same time there is a commercial demand for low filament deniers. It has been found that with increasing spinning speeds, it has become increasingly difiicult to draw down the filaments so as to obtain low deniers, that is to say the draw down attainable at high speeds appears to be less than the draw down obtainable at low speeds using the same spinning solution and the same jet orifices. It is possible to obtain products of low denier at high spinning speeds by decreasing the concentration of the cellulose acetate or other cellulose derivatives'in the spinning solution. Unfortunately this revives the old difiiculty of the cross-section of the filaments, since the fiat filaments with their attendant disadvantages such as scintillation reappear. Further, with increasing speeds, it is of course possible to decrease the size of the jet orifices so as to obtain products of low denier, but mechanical considerations put a limit to the extent to which the size of the jet orifice can be diminished.

We have now found, and this forms the basis of the present invention, that filaments of low denier, having a good cross-section and therefore comparatively little liable to scintillation when made into fabrics, can be produced at relatively high speeds by means of spinning solutions of relatively low concentration but of high viscosity. Thus, for example, the concentration may be 25 to 20 or 15% or less by weight of 55 the cellulose acetate or other cellulose ester or ether on the weight of the spinning solution. With such spinning solutions low filament deniers of good cross-section may be obtained at high spinning speeds without decreasing the size of 550 the spinning orifices or even with spinning orifices larger than normal. Preferably the solutions employed have a viscosity of 1 -2 or more times that of the normal spinning solutions, particularly when the solution contains 23% or less of the cellulose acetate or other base.

Various means may be adopted to increase the Viscosity of the spinning solution. For instance, a cellulose derivative of high viscosity characteristics may be employed, without applying any special process for decreasing the viscosity of the spinning solution such as is described in U. S. Patent No. 1,872,701. The best method which we have found for the purpose of obtaining filaments of comparatively round cross-section from relatively dilute solutions consists in making up the spinning solution with the aid of an agent which increases the viscosity of the said solution, and, if desired, this method may be combined with the use of high viscosity cellulose derivatives, such as are described in U. S. Patent No. 1,708,787. The agents are such that together with the solvent in the spinning solution they yield a solution of substantially higher viscosity than a solution of the same cellulose derivative of the same concentration in the solvent alone. In general such agents are non-solvents for the cellulose derivative and they may for example be strongly acting precipitants, e. g. the hydrocarbons in the case of the lower aliphatic esters of cellulose, weakly acting precipitants or substances which are swelling or gelling agents for the cellulose derivatives, e. g. the alcohols, or which are latent solvents, that is to say are practically solvents, for instance methylene chloride or ethyl acetate for acetone-soluble cellulose acetate.

As is well known, some agents which are nonsolvents for the cellulose derivative, as, for example, alcohols or water, when added to an acetone solution of an acetone-soluble cellulose acetate decrease the viscosity of the spinning solution, or, in other words, acetone containing a small amount of water, alcohol or like agent is a better solvent for the cellulose acetate than is acetone alone. Such agents may be employed according to the present invention in order to increase the viscosity of the spinning solution, but it will be appreciated that they must be employed in a much greater proportion than that which produces with the solvent the highest solvent power for the cellulose derivative. Thus, for instance, in the case of using a particular cellulose acetate, which gives a solution of minimum viscosity in acetone containing 15% of ethyl alcohol, the proportion of alcohol to be used in accordance with the present invention must be much greater than 15% of the total solvent mixture and is preferably considerably greater, for example 25% or more.

Other agents which may be employed in ac;

cordance with the present invention, particularly for the acetone-soluble type of cellulose acetate or nitro-acetate, are methyl acetate, ethyl acetate, ethyl formate, methyl alcohol, water, benzene, toluene, xylene, suitable petroleum fractions, methylene chloride, ethylene chloride, chloroform, dichlorethylene, trichlorethylene, methyl ethyl ketone, diethyl ketone, and the like. Agents such as benzene and ethyl acetate are preferable with acetone and an acetone-soluble cellulose acetate, since even small additions to the acetone produce a solution of cellulose acetate of higher viscosity than the simple acetone solution, so that relatively small proportions may substantially increase the viscosity of the spinning solution. Mixtures of any of the above agents may of course be employed.

Thus, for example, We have found that very good results may be obtained, including filament deniers of l or 1.5 to 2 or 2.5 of good cross-section, at high spinning speed using spinning solutions containing 15-23% and especially 18-20- 23% of acetone-soluble cellulose acetate (containing about 54% of combined acetic acid) dissolved in a solvent mixture consisting of 5-l0% of water, -80% of an 80:20 mixture of methyl acetate and methyl alcohol, and the remainder acetone; or dissolved in a mixture consisting of 5-10% of water, 20 to 30% and upwards of an 85:15 mixture of ethyl acetate and .ethyl alcohol, and the remainder acetone; or dissolved in a mixture of 5-10% of water, 1.2% and upwards of ethyl acetate and the remainder acetone; or dissolved in a mixture of 5-10% of water, -25% or more of methyl alcohol and the remainder acetone. Similarly, using the same concentrations of a cellulose acetate of 48 to 50% acetic acid content, good results may be obtained with a solvent mixture containing acetone, benzene and alcohol, e. g. in the proportions 50:28:22.

It will be noted that the large majority of the above mixtures contain water and in fact we have found that the presence of water in such mixtures much facilitates the draw-down.

Though the above invention has been described more particularly with reference to acetone-soluble cellulose acetate it may be equally well utilized for the purpose of producing low filament deniers or other products of small cross-section at high speed from other cellulose acetates and from other cellulose esters, as for example cellulose-formate, cellulose propionate, cellulose butyrate or nitro-acetate, from cellulose ethers, for instance methyl cellulose, ethyl cellulose or benzyl cellulose, from ether-esters of cellulose, and from mixed .esters and mixed ethers of cellulose.

The following example is given in order to illustrate the invention, but it is to be clearly understood that they do not limit it in any way:-

Example A 22%23% solution of cellulose acetate in a solvent mixture consisting of 65-75% acetone, -30% ethyl alcohol and 5% water is spun according to dry spinning methods into an evaporative medium. A fine denier yarn of good crosssection is obtained.

Theabove example may be modified by the use instead of a solvent mixture consisting of 40% methyl acetate, 20% methyl alcohol, 5% water and 35% acetone, or of 82% acetone, 6% water and 12% benzol, or of 80% acetone, 15% methyl alcohol and 5% of Water. In each case fine denier filaments of good cross-section may be obtained.

In the above examples the cellulose acetate employed gives a solution of minimum viscosity in acetone containing 5-7% of water and the spinning solutions used have a viscosity of more than 1 times and generally about twice that of said solution of minimum viscosity.

What we claim and desire to secure by Letters Patent is:

1. Process for the manufacture of lustrous artificial filaments by a dry spinning method, which comprises spinning, at a speed of at least 180 metres per minute, a solution of an organic derivative of cellulose, of 20-25% concentration, in a solvent medium containing a solvent for the organic derivative of cellulose and an organic diluent of low solvent power for the organic derivative of cellulose, in quantity to impart to the said solution an increased viscosity, as compared with a solution of the said cellulose derivative, of the same concentration, in the solvent alone.

2. Process for the manufacture of lustrous artificial filaments by a dry spinning method, which comprises spinning, at a speed of at least 180 metres per minute, a solution of an organic derivative of cellulose, of 20-2-5% concentration, in a solvent medium containing a solvent for the organic derivative of cellulose and an organic diluent of low solvent power for the derivative of cellulose, in such proportions that the viscosity of the said solution is at least 1 times that or" a solution of the said cellulose derivative, of-the same concentration, in the solvent alone.

3. Process for the manufacture of lustrous artificial filaments by a dry spinning method, which comprises spinning, at a speed of at least 180 me tres per minute, a solution of a high viscosity organic derivative of cellulose, or" 20-25% concentration, in a solvent medium containing a solvent for the organic derivative of cellulose and an organic diluent of low solvent power for the derivative of cellulose, in such proportions that the viscosity of the said solution is at least 1 times that of a solution of the said cellulose derivative, of the same concentration, in the solvent alone.

4. Process for the manufacture of lustrous artificial filaments by a dry spinning method, which comprises spinning, at a speed of at least 180 metres per minute, a solution of a high viscosity organic derivative of cellulose, of 20-25% concentration, in a solvent medium containing a solvent for the organic derivative of cellulose and an organic ester which is of low solvent power for the said cellulose derivative, in such proportions that the viscosity of the said solution is at least twice that of a solution of the said cellulose derivative, of the same concentration, in the solvent alone. 7

5. Process for the manufacture of lustrous artificial filaments by a dry spinning method, which comprises spinning, at a speed of at least 180 metres per minute, a solution of a high viscosity organic derivative of cellulose, of 20-25% concentration, in a solvent medium containing a solvent for the organic derivative of cellulose and an alcohol which is of low solvent power for the said cellulose derivative, in such proportions that the viscosity of the said solution is at least twice that of a solution of the said cellulose derivative, of the same concentration, in the solvent alone.

6. PI'OlCBSS for the manuiactfure of lustrous artificial filaments by a dry spinning method, which comprises spinning, at a speed of at least 180 metres per minute, a solution of a high viscosity organic derivative of cellulose, of 20-25% concentration, in a solvent medium containing a solvent for the organic derivative of cellulose and an aromatic hydrocarbon which is of low solvent power for the said cellulose derivative, in such proportions that the viscosity'of the said solution is at least twice that of a solution of the said cellulose derivative, of the same concentration,

in the solvent alone. a

'7. Process for the manufacture of lustrous artificial filaments by a dry spinning method, which comprises spinning, at a speed of at least 180 metres per minute, a solution of cellulose acetate, of 20-25% concentration, in a solvent medium containing a solvent for the cellulose acetate and an organic diluent of low solvent power for the cellulose acetate, in quantity to impart to the said solution an increased viscosity as compared with a solution of the said cellulose acetate, of the same concentration in the solvent alone.

8. Process for the manufacture of lustrous artificial filaments by a dry spinning method, which comprises spinning, at a speed of at least 180 metres per minute, a solution of cellulose acetate, of 20-25% concentration, in a solvent medium containing a solvent for the cellulose acetate and an organic diluent of low solvent power for the cellulose acetate, in such proportions that the viscosity of the said solution is at least 1 times that of a solution of the said cellulose acetate, of the same concentration, in the solvent alone.

9. Process for the manufacture of lustrous artificial filaments by a dry spinning method, which comprises spinning, at a speed of at least 180 metres per minute, a solution of a high viscosity cellulose acetate, of 20-25% concentration, in a solvent medium containing a solvent for the cellulose acetate and an organic diluent of low solvent power for the cellulose acetate, in such proportions that the viscosity of the said solution is at least 1% times that of a solution of the said cellulose acetate, of the same concentration, in the solvent alone.

10. Process for the manufacture of lustrous artificial filaments by a dry spinning method, which comprises spinning, at a speed of at least 180 metres per minute, a solution of a high viscosity cellulose acetate, of 20-25% concentration, in a solvent medium containing a solvent for the cellulose acetate and an organic ester which is of low solvent power for the said cellulose acetate, in such proportions that the viscosity of the said solution is at least twice that of a solution of the said cellulose acetate, of the same concentration, in the solvent alone.

11. Process for the manufacture of lustrous artificial filaments by a dry spinning method, which comprises spinning, at a speed of at least 180 metres per minute, a solution of a high viscosity cellulose acetate, of 20-25% concentration, in a solvent medium containing a solvent for the cellulose acetate and an alcohol which is of low solvent power for the said cellulose acetate, in,

cellulose acetate and'an aromatic hydrocarbonwhich is of low solvent power for the said cellulose acetate, in such proportions that the viscosity of the said solution is at least twice that of a solution of the said cellulose acetate, of the same concentration, in the solvent alone.

13. Process for the manufacture of lustrous artificial filaments by a dry spinning method, which comprises spinning, at a speed of at least 3.00 metres per minute, a solution of cellulose acetate, of 20-25% concentration, in a solvent medium comprising acetone, containing 5-'7% of water, and ethyl alcohol in such proportions that the viscosity of the said solution is at least twice that of a solution of the said cellulose acetate, of the same concentration, in acetone containing 5-7% of water.

14. Process for the manufacture of lustrous artificial filaments of round cross section by a dry spinning'method, which comprises spinning at a speed of at least 180 metres per minute under conditions such that lustrous filaments are formed, a solution of organic derivative of cellulose of 20-25% concentration in a solvent medium containing a solvent for the organic derivative of cellulose and an organic diluent of low solvent power for the organic derivative of cellulose, in uantity to impart to said solution an increased viscosity as compared with a solution of said cellulose derivative of the same concentration in the solvent alone.

15. Process for the manufacture of lustrous artificial filaments of round cross section by .a dry spinning method, which comprises spinning at a speed of at least 180 metres per minute under conditions such that lustrous filaments are form-ed, a solution of cellulose acetate of 20-25% in a solvent medium containing a solvent for the cellulose acetate and an organic diluent in such proportions that the viscosity of the said solution is at least 1 times that of a solution of said cellulose acetate of the same concentration in the solvent alone.

16. Process for the manufacture of lustrous artificial filaments of round cross section by a .ry spinning method, which comprises spinning at a speed of at least 180 metres per minute under conditions such that lustrous filaments are formed, a solution of cellulose acetate of 20-25% concentration in a solvent medium containing a solvent for the cellulose acetate and an organic ester which has a low solvent power for the cellulose. acetate in such proportions that,

the viscosity of the said solution is at least twice that of the solution of said cellulose acetate of the same concentration in the solvent alone.

17. Process for the manufacture of lustrous artificial filaments of round cross section by a dry spinning method, which comprises spinning at a speed of at least 180 metres per minute under conditions such that lustrous filaments are formed, a solution of cellulose acetate of 20-25% concentration in a solvent medium containing solvent for the cellulose acetate and an alcohol which has a low solvent power for the said cellulose acetate in such proportions that the viscosity of the said solution is at least twice that of the solution of said cellulose acetate of the same concentration in the solvent alone.

HENRY DREYFUS. WILLIAM IVAN TAYLOR.

CERTlFICATE OF CORRECTION. Patent No. 2,o9-L ,78o. October 5, 1957.

HENRY DREYFUS, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, second column, line 59, claim 15 (after diluent" insert the words of low solvent power for the cellulose acetate; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 16th day of November, A. D. 1957 Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

